[squeak-dev] for the operation MAP := B bitOr:( M bitShift:3) given MAP how do I derive B and M?

Jecel Assumpcao Jr. jecel at merlintec.com
Thu Feb 13 14:36:52 UTC 2014


Tim Rowledge observed:
> Which is all well and good until you run out of 1's, like we sometimes
> used to when I was a young'un trudging to school barefoot
> in the snow, uphill both ways.

Ron Teitelbaum exclaimed:
> You had FEET?

Eliot Miranda clarified:
> yes, but there was only the one pair to share between all 17 siblings... 

You guys are being silly, but when I was in the first year of the
university I actualy kept a bag full of 1s. The computer was a Burroughs
B6700 and students had to use punched cards to program it (this was
replaced with terminals the following year). While on normal days the
both the card reader/printer room and the keypunch room were deserted,
on the due dates for student projects the lines were Disney-level long.
To have a faster turn-around for small edits, I had previously collected
a bag full of chad from the keypunch machine (the 1s), had typed a card
with all characters to have a reference for the codes and had a razor
blade for cutting new holes (the 0s). There was no need for tape or
anything like that to keep the chad in the covered up holes as the card
went through the reader: both the hole and the chad had rough borders
and rubbing a fingernail on them on a smooth surface would expand them
slightly.

-- Jecel
p.s: the 1s and 0s in this story are probably inverted - just apply XOR
1 and it will be true



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